Boot a guest VM from CD or DVD in XenServer

In order to boot from cd or dvd you need to change the guest virtualization type from HVM (fully virtualized) to PV (paravirtualized).

$ sudo xenstore-read vm | xargs -n1 basename
54a95df1-d4f3-67f7-46d3-6dcd1d1143ab

xe vm-param-set HVM-boot-policy="BIOS order" uuid=[uuid of your vm]

After you have booted from dvd, change back to fully virtualized mode:

xe vm-param-set HVM-boot-policy="" uuid=[uuid of your vm]

Read more about difference between HVM and PV:

http://serverfault.com/questions/222010/difference-between-xen-pv-xen-kvm-and-hvm